| 摘要 |
This invention relates to a compound of formula (I) and its pharmaceutically acceptable salt, to processes for preparation thereof, to pharmaceutical composition comprising the same, and to a method for preventing and/or treating infectious diseases in human beings and animals. In said formula (I), R<1> is amino or protected amino, R<2> is ethyl, propyl, cyclo(lower)alkyl, 1-methylpropenyl or 2-methylpropenyl, R<3> is hydroxy(lower)alkyl or protected hydroxy(lower)alkyl, and R<4> is amino or protected amino. |
